JPS6053449B2 - Manufacturing method of split type zero-phase current transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for manufacturing a split zero-phase current transformer.

In general, a split type zero-phase current transformer is constructed by tightening and fixing flanges 1a and 1a formed on a pair of semicircular arc-shaped electromagnetic inductors 1 and 1, respectively, as shown in Figures 1 and 2. It is assembled.

Each derivative 1 is [Kura! , 台＾ , ゛“, ゛toILl
ιil yo w↓ Δ1^ ri □ 1, 8, -, surrounds the IV port 1 and fitting 4, and further accommodates this in a semicircular arc molded case 5, and injects epoxy resin, etc. into the case 5. The iron cores 3, 3 exposed from the molded cases 5, 5 and the shield fittings 4, 4 come into contact with each other when the respective dielectrics 1, 1 are assembled into an annular shape. ing.

This split type zero-phase current transformer is installed to surround existing wiring installed in, for example, hotels, theaters, factories, etc., and is often used as an earth leakage sensing device for detecting earth leakage.

Therefore, the zero-phase current transformer can detect minute ground leakage currents in as high a frequency range as possible, does not malfunction due to external induction, and is stable even when there are changes in the environment of the installation site, season, temperature, etc. There is a demand for highly accurate devices with sensitive sensitivity characteristics. For this reason, conventionally, a high-precision split type zero-phase current transformer was manufactured using a ring-shaped iron core in which a pair of windings 2 and 2 were wound separately and surrounded by a ring-shaped shielding metal fitting. After that, it is housed in an annular mold case, and a hardening resin 6 such as epoxy resin is injected into the case and solidified, and then it is cut and divided into two parts.Then, the cut mold case is divided into two parts. The iron cores 3, 3 and the metal fittings 4, 4 for shielding and shielding are manufactured by polishing their respective surfaces so as to protrude by a predetermined height from the dividing surface of the molded case.

Since the split type zero-phase current transformer manufactured in this way is formed by cutting the annular iron core and the annular shield fitting, the accuracy of each inductor 1, 1 is high, and each inductor 1, 1
When assembled into an annular shape, only the iron cores 3, 3 and the shield fittings 4, 4 are in pressure contact, and the mold cases 5, 5 are separated, so the mold cases 5,
Even when the cores 5 expand or contract, the cores 3 and 3 do not separate from each other, and stable sensitivity characteristics can be obtained. However, in the conventional method described above, the mold case 5,
Since the mold cases 5, 5, the shield fittings 4, 4, and the iron cores 3, 3 are flush with each other when the parts 5, etc. are cut, these are left when the shield fittings 4, 4 and the iron cores 3, 3 are made to protrude. Therefore, the mold cases 5, 5 had to be polished, and the polishing work was time-consuming.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a method for manufacturing a divided zero-phase current transformer that can easily manufacture a highly accurate divided zero-phase current transformer. It is something.

That is, in the present invention, a pair of conductive wires is separately wound and 80% by weight is used.
After surrounding a shielding metal fitting on the outside of an annular iron core made of an alloy having a composition of Ni, 5% by weight MO, and 15% by weight Fe, this was housed in a molded case, and then a synthetic resin was injected into the case and solidified. After cutting and separating the annular core and the shield fitting, the annular core surrounding the shield fitting is cut into a pair of semicircular arc-shaped molded cases arranged in a ring. After the case is housed in the case, the case is fixed so that the opposing surfaces thereof are separated by a predetermined distance, and after a synthetic resin is injected and solidified into the case, the annular iron core and the shielding metal fittings are inserted along the gap between the two cases. Cut and separate the annular core and shield fittings. This is a method of manufacturing a split type zero-phase current transformer, characterized in that the surface protrudes from the opposing surface of the molded case by a predetermined height. Embodiments of the method of the present invention will be described in detail below with reference to the drawings.

First, as shown in Figure 3, 80 wt% Ni and 5 wt% MO
The outer periphery of an annular iron core 3'' made of a high permeability magnetic material called Super Malloy (trade name), which is an alloy with a composition of 1% Fe, is insulated, and a pair of conductive wires 2 are connected to this iron core 3''. ,2
are separated and wound, and furthermore, these conductive wires 2, 2 are insulated.

In this state, a pair of semi-circular arc parts 3a, 3a around which the conductive wire 2 is wound are formed on the iron core 3'', and the conducting wires 2, 2 are wound between these semi-circular arc parts 3a, 3a. There are two locations at symmetrical positions on the iron core 3''. In this case, the width of the part where the conducting wires 2, 2 are not wound is about the cutting allowance when cutting the iron core 3'' in a later process. A hollow annular shield fitting 4 consisting of a pair of annular members 4a, 4a formed in the shape of a mouth is surrounded by the members 4a, 4a with a gap between them. This shield fitting 4 is 45
The iron core 3'' is made of a high permeability magnetic material such as a Ni-Fe alloy and is designed to prevent the iron core 3'' from receiving electromagnetic force from the outside.Then the iron core 3'' surrounded by the shield fitting 4 is It is housed in a pair of semicircular arc molded cases 5, 5 arranged in an annular manner.

In this case, the iron core 3'' is housed so that the part where the conductive wires 2, 2 are not wound is located between the opposing surfaces of the molded cases 5, 5, and the shielding fitting 4 and the conductive wire 2, The gap between the parts where 2 is not wound is filled with silicone resin. Further, after housing the iron core 3'' etc. in the molded cases 5, 5, an intervening plate 9 as shown in FIG. , 5a with bolts 8, 8.In this case, the intervening plate 9 and the surfaces of the cases 5, 5 in contact therewith are coated with silicone resin as a mold release agent and a sealing material, and the intervening plate 9 is then fixed. The plate 9 is formed to have a thickness equal to the sum of the cutting allowance and the polishing allowance when cutting and polishing the iron core 3'' etc. in a subsequent process. Further, the intervening plate 9 is formed by being divided into upper and lower parts, and when combined, they form through holes 9a, 9a through which the shield fitting 4 passes, and bolt insertion holes 9a, 9b. After the molded cases 5, 5 are tightened and fixed via the intervening plate 9, a hardening resin such as epoxy resin is vacuum injected into the cases 5, 5, and the shielding fittings 4 are connected to the cases 5, 5. The resin is filled and solidified into the space between the shield metal fitting 4 and the iron core 3'', respectively, and the iron core 3'' and the shield metal fitting 4 are fixed to the molded cases 5, 5.

In this case, silicone resin is filled between the iron core 3'' and the shield fitting 4, and since the silicone resin is applied to the intervening plate 9 and the cases 5, 5, the molded cases 5, 5
The joints are sealed and the curable resin will not leak out from there. Next, after removing the intervening plate 9 and forming a gap of a predetermined width between the molded cases 5 and 5, the shield fitting 4 and the iron core 3'' are divided into two parts along the gap formed here. In this state, the cut surfaces of the shielding fittings 4, 4 and the iron cores 3, 3 protrude from the opposing surfaces of the molded cases 5, 5. Therefore, in the method of the present invention, the molded cases 5 are cut as in the conventional method. There is no need to polish the opposing surfaces of the mold cases 5, 5.
Shield fittings 4, 4 and iron core 3 protruding from the opposing surfaces of
, 3 are polished to a predetermined height, and after this polishing, only the shield fitting 4 is re-polished to a depth of about 10 microns, for example. This is 80Ni-5M0-F that constitutes iron core 3
The expansion coefficient of the e-alloy is 16 x 10-6 cm1deg1 The expansion coefficient of the 45Ni-Fe alloy that constitutes the shield fitting 4 is 7.
×10-6c! This is because it is different from Itldeg,
By making the shield fitting 4 slightly shorter, the iron core 3
Even if the iron cores 3, 3 expand or contract, the iron cores 3, 3 do not become separated, and their sensitivity characteristics can be maintained well. After the above-mentioned polishing, the silicone resin adhering to the cases 5, 5 is removed and the upper surfaces of the openings of the molded cases 5, 5 are covered, thereby manufacturing the split type zero-phase current transformer according to the present invention. Note that the method of the present invention involves injecting a hardening resin such as epoxy resin between the iron core 3'' and the shield fitting 4 and between the shield fitting 4 and the molded cases 5, 5, respectively, as in the above embodiment. After filling and solidifying the shield metal fitting 4 and iron core 3'',
Not limited to the method of cutting into parts, for example, iron core 3"
A flexible resin such as silicone resin is filled in advance between the iron core 3'' and the shielding fitting 4 that surrounds it to integrate the iron core 3'' and the shielding fitting 4, and then this is placed in a molded case 5.
, 5 and the shield fitting 4 and the mold case 5
, 5 may be filled and solidified with epoxy resin, etc., and then the shield fitting 4 and the iron core 3'' may be cut into two parts. According to this method, the resulting zero-phase current transformer Since flexible resin is filled between the iron cores 3, 3 and the shielding fittings 4, 4, it absorbs and alleviates the strain caused by thermal expansion of the iron cores 3, 3 and the shielding fittings 4. The precision of the zero-phase current transformer is high because the tools 4 and 4 are always in close contact with each other.According to the present invention, when an extremely soft 80Ni-15F'e alloy is used for the iron core, remarkable effects can be achieved. .

That is, FIG. 5 shows the change in magnetic flux density when the magnetic field strength (H) is changed.

This figure shows that in the case of "annealed silicon steel...A", the decrease in magnetic flux density is large when the magnetic field strength is small, whereas "in the case of heat-treated silicon steel with the alloy composition used in the present invention" Things, the so-called supermalloy...B"
has a high magnetic flux density even if the magnetic field strength is small. For example, at a magnetic field strength of 0.004 Oe, silicon steel has a magnetic flux density of 10 Gauss, whereas the heat-treated alloy used in the present invention has a magnetic flux density of 400 Gauss, which is approximately 4(1) times more excellent. Therefore, the iron core with the alloy composition used in the present invention can be effectively used in earth leakage detection devices that must detect minute ground leakage currents with high sensitivity, and this The one used cannot be substituted.

However, the alloy used in the present invention is an extremely soft material, whereas silicon steel is a hard material.

In the case of silicon steel, since it is hard, it is difficult to deform even if the core is cut, and the magnetic properties do not deteriorate much, so there is no need to pay particular attention to the cutting process. On the other hand, the alloy used in the present invention is easily deformed during the manufacturing process, particularly during the cutting process, and its magnetic properties are significantly deteriorated. For example, when a split type zero-phase current transformer similar to the present invention is manufactured by the usual method of impregnating an iron core with epoxy resin and cutting it, the magnetic characteristics after impregnation (before cutting) are B→ It decreases to C. After cutting, the magnetic properties further deteriorate from B to C+D as shown by curve D. Therefore, the properties are not much different from those of silicon steel, and it cannot be used for the above-mentioned purposes. Therefore, the present invention
In order to solve the problem of deterioration of magnetic properties that occurs when cutting and dividing, a ring core made of 80Ni-15F'e alloy is fixed with a pair of molded cases, shielding metal fittings, and synthetic resin. The molded case is separated for a predetermined period of time, and in the final step in this state, the annular core is cut and separated, thereby preventing deformation and minimizing deterioration in accuracy.

For example, the split zero-phase current transformer obtained by the method of the present invention, as shown in curve E, has almost the same characteristics as the one impregnated with epoxy resin before cutting (curve C), and has a magnetic flux density of 0.004 Oe. Approximately 8＠ compared to silicon steel ones
, is more than twice that of the normal method (curve D). As explained above, according to the present invention, the core, etc. is cut using a pre-divided mold case with the two facing each other at a predetermined interval, so it is not necessary to polish the divided surfaces of the mold case as in the conventional method. This eliminates this problem, making it possible to easily manufacture a highly accurate split-type zero-phase current transformer.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a split type zero-phase current transformer according to the present invention, and FIG.
The figure is a sectional view taken along the line ■-■ in FIG. - Figure 5 shows the relationship between the magnetic field strength and magnetic flux density of the iron core according to the method of the present invention.
FIG. 2 is a characteristic diagram showing a comparison between an iron core made of a Ni-15F'e alloy and an iron core obtained by a conventional method. 1...Split type, 2...Conductor, 3...
...Iron core, 4...Wood fittings, 5...
...Mold case, 6...Curing resin, 9.
...Intervening plate.

Claims (1)

[Claims] 1 A pair of conducting wires are separately wound, and a shielding metal fitting is surrounded on the outside of an annular iron core made of an alloy having a composition of 80% Ni, 5% Mo, and 15% Fe, and then this is housed in a molded case. Then, after injecting and fixing the synthetic resin into the case, when cutting and separating the annular core and the shield fitting, the annular core surrounding the shield fitting is cut into a pair of halves arranged in a ring. After being housed in an arcuate molded case, the case is fixed so that its opposing surfaces are spaced apart by a predetermined distance, and then a synthetic resin is injected into the case and solidified, and then the annular core and shielding metal fittings are attached to both cases. A method of manufacturing a split type zero-phase current transformer, characterized in that the annular core and the shielding metal fittings are cut and separated along the interval portions so that the cut surfaces of the annular core and the shielding metal fittings protrude from the opposing surface of the molded case by a predetermined height.